1. Field of the Invention
The present invention relates to a connector including a socket and plug for allowing a portable electric appliance having an internal power supply to use an external power supply, and more particularly to a connector capable of switching a first operation of the electric appliance with the use of the internal electric supply to a second operation thereof with the use of the external power supply in response to a connection of the socket with the plug.
2. Disclosure of the Prior Art
A portable electric appliance such as a radiotelephone can be generally operated by an internal power supply, e.g., a rechargeable battery built in the radiotelephone or a battery pack detachably mounted thereon. The internal power supply can be charged by application of a suitable DC charging unit. However, the internal power supply would not always be enough to use the electric appliance continuously for an extended time period. For example, when a portable radiotelephone is used in a car, it would be preferred that the radiotelephone is operated by electric power supplied from an external power supply such as a cigarette lighter socket or fuse box carried in the car without using the internal power supply.
Japanese Patent Early Publication [KOKAI] No. 05-174905 proposes a connector 1E including a socket 2E mounted in a portable radiotelephone 4E having an internal power supply E1 and a plug 3E used for supplying electric power from an external power supply E2. As shown in FIGS. 24 and 26, the socket 2E is formed with a socket housing 10E having a rectangular concave 11E, socket terminals 12E projected in the concave, or recess, 11E, a pair of charging terminals 13E projected on the socket housing 10E, movable terminal member 20 E and a stationary terminal strip 30E. The movable terminal member 20E is formed with a base plate 21E to be fixed on the socket housing 10E, and a torsion arm 22E extending from the base plate 21E. The torsion arm 22E has a movable contact 23E. The stationary terminal member 30E is disposed in the socket housing 10E such that the movable contact 23E is urged against the stationary terminal strip 30E by spring bias of the torsion arm 22E to make a first electrical connection therebetween. Therefore, when the plug 3E is not connected to the socket 2E, it is possible to perform a first operation of the radiotelephone 4E with the use of the internal power supply El, as shown in FIG. 25. Numeral 5E designates a drive circuit of the radiotelephone 4E. The charging terminals 13E are adapted to be connected to a suitable DC charger (not shown) for charging the internal power supply El.
The plug 3E is formed with a plug housing 40E having a rectangular convex, or protrusion 41E, power chord 42E to be detachably connected to the external power supply E2, plug terminals 43E arranged in the convex 41E, and a switch portion 45E formed with an inclined wall of the convex 41E. When the convex 41E of the plug 3E is inserted in the concave 11E of the socket 10 E, a second electrical connection between the socket and plug terminals (12E and 43E) is made to perform a second operation of the radiotelephone 4E with the use of the external power supply E2. At the same time, since the torsion arm 22E is moved along the inclined wall 45E such that the movable contact 23E is spaced away from the stationary terminal strip 30E, as shown in FIGS. 26 and 27, the first electrical connection can be broken in response to the connection of the plug 3E to the socket 2E. In other words, the first operation of the radiotelephone 4E with the use of the internal power supply E1 can be switched to the second operation thereof with the use of the external power supply E2 by connecting the plug 3E to the socket 2E of the radiotelephone 4E.
By the way, in case of using the above explained radiotelephone, there often causes a problem that dust or pieces of thread of a clothing, carpet, or the like, is accidentally put between the movable contact 23E and the stationary terminal strip 30E, so that the first electrical connection is broken to prevent the first operation of the radiotelephone 4E. Particularly, it is confirmed that such a problem is caused by a piece of thread having a length more than about 5 mm and a diameter more than about 20 .mu.m. For example, when a piece of thread having about 20 .mu.m is accidentally put between the movable contact 23E and the stationary terminal strip 30E, it is squeezed by the spring bias of the torsion arm 22E to form a thread sheet having a thickness of about 3 to 5 .mu.m. The first electrical connection is broken by thus formed thread sheet with a considerable probability.